I suggest a truggy for you.
Monster trucks are the bread and butter of go anywhere vehicles but IMO pavement running with them isn't very fun. Their higher center of gravity makes it easy for them to traction roll and without a lot of suspension tweaking and tuning they just don't handle that great on-road. Hence they aren't very enjoyable if you're going to spend a lot of time on pavement.
Buggies are also great go anywhere vehicles but because they are race-bred they are relatively low to the ground. If you plan on running quite a bit in the grass this isn't necessarily a great choice because the lower ride height of a buggy will bog down in medium to tall grass..
Truggies offer the best of both. They will handle much better on pavement because of the way their components are laid out. The center of gravity is much lower than a monster truck. But because they use a much taller tire than a buggy they don't get swamped in average height grass like a buggy may.
Here's a couple for you to look at that I'm NOT familiar with
http://www.amainhobbies.com/product_info.php/cPath/1_44_50/products_id/12363
http://www.amainhobbies.com/product_info.php/cPath/1_44_50/products_id/33276
I can personally recommend the Thunder Tiger ST-1 truggy. I have the buggy version and it's pretty damn tough. I have a couple upgrades but not much and even if you did upgrade the same parts I have you would still be well under $500
TTR ST-1 RTR
$300
http://www.amainhobbies.com/product_info.php/cPath/1_44_50/products_id/17281
Front/Rear suspension plate
$23
http://www.amainhobbies.com/product_info.php/cPath/1_24_178/products_id/2535
Rear/Rear suspension plate
$23
Steering
$56
http://www.amainhobbies.com/product_info.php/cPath/1_24_178/products_id/2542
That's only $400 and you'll have one tough truck I guarantee. Every magazine article that I've ever read about the St-1 raved about it's durability. RC Driver, RCCA, XRC.. all the big ones. This is a very underated truck in my opinion.
...and if my opinion isn't good enough... Read the reviews...
http://www.amainhobbies.com/product_reviews.php/cPath/1_44_50/products_id/17281
BTW- Thunder Tiger owns Associated Electronics so the radio gear you get is the same as what comes with all the AE RTR's except it's branded differently. It's a standard AM radio system but with $100 left in your budget you have a good head start at a nice FM or even 2.4ghz system